📚 Year 11 OCR Physics: Core Knowledge Summary | Year 11 OCR 物理：核心知识点梳理
Year 11 OCR Physics brings together the key principles that explain how the universe behaves – from the motion of a falling apple to the dance of galaxies. This summary distils the essential ideas you need to master: energy transfers, electricity, forces, waves, radioactivity, and more. Whether you are revising for mocks or final exams, these concise explanations will reinforce your understanding and boost your confidence.
Year 11 OCR 物理汇集了从下落的苹果到星系运动的关键原理，解释宇宙如何运行。这份梳理提炼了你必须掌握的核心概念：能量传递、电学、力、波、放射性等等。无论你是在准备模拟考试还是最终大考，这些简洁的讲解都将巩固你的理解并提升信心。
1. Energy Stores and Transfers | 能量的储存与转移
Energy is a quantity that is always conserved: it cannot be created or destroyed, only transferred between different stores. In OCR Physics, you must know the main energy stores – kinetic, gravitational potential, elastic potential, thermal (internal), chemical, nuclear, magnetic, and electrostatic – and the pathways for transfer: mechanical work, electrical work, heating, and radiation.
能量是一个总是守恒的量：它不能被创造或消灭，只能在不同能量储存之间转移。在 OCR 物理中，你必须了解主要的能量储存——动能、重力势能、弹性势能、热（内）能、化学能、核能、磁能和静电储存——以及转移途径：机械做功、电做功、加热和辐射。
- lastic potential energy Eₑ = ½ke² (provided the limit of proportionality is not exceeded).
- 动能 Eₖ = ½mv² ，重力势能 Eₚ = mgh ，弹性势能 Eₑ = ½ke² （前提是不超过比例极限）。
Always identify the system and the initial and final stores when solving energy problems. Efficiency is the ratio of useful output energy (or power) to total input energy (or power), often expressed as a percentage.
解决能量问题时，务必明确系统、初始能量储存和最终能量储存。效率是有用输出能量（或功率）与总输入能量（或功率）的比值，常用百分数表示。
2. Work Done and Power | 做功与功率
ule is the work done when a force of 1 newton moves its point of application 1 metre in the direction of the force.
当一个力使物体移动时，就做了机械功。做功 W = Fd（力 × 沿力方向移动的距离）。1 焦耳就是 1 牛顿的力使作用点沿力方向移动 1 米所做的功。
e found as the product of force and velocity when the force is constant and parallel to the motion.
功率是能量传递或做功的速率：P = E/t 或 P = W/t。单位是瓦特 (W)，1 W = 1 J/s。在力学中，当力恒定且与运动方向平行时，功率也可表示为力与速度的乘积。
3. Electricity: Charge, Current and Potential Difference | 电学：电荷、电流与电势差
ent direction is opposite to electron flow. For a given component, resistance R = V/I; ohm' or at constant temperature is directly proportional to the potential difference across it.
电流是电荷流动的速率：I = ΔQ/Δt。在金属中，电荷载流子是自由电子。按照惯例，电流方向与电子流动方向相反。对于给定元件，电阻 R = V/I；欧姆定律指出，在恒定温度下，通过电阻器的电流与其两端的电势差成正比。
The behaviour of ohmic conductors, filament lamps, and diodes must be understood through their I–V graphs. A thermistor has a resistance that decreases with temperature; an LDR (light-dependent resistor) has a resistance that decreases with light intensity. In series circuits, current is the same everywhere, potential difference is shared, and total resistance is the sum of individual resistances. In parallel circuits, the potential difference across each branch is the same, total current is the sum of branch currents, and total resistance is less than the smallest individual resistance.
必须通过 I–V 图理解欧姆导体、灯丝灯泡和二极管的特性。热敏电阻的阻值随温度升高而减小；光敏电阻 (LDR) 的阻值随光照强度增加而减小。串联电路中，各处电流相等，电压按比例分配，总电阻为各电阻之和。并联电路中，各支路电压相同，总电流为各支路电流之和，总电阻小于最小的单个电阻。
4. Domestic Electricity and Energy Transfers in Circuits | 家庭用电与电路中的能量转移
Mains electricity in the UK is an alternating current (a.c.) at about 230 V with a frequency of 50 Hz. Household wiring uses a ring main circuit with a live wire (brown), neutral wire (blue), and earth wire (green/yellow). The earth wire is a safety feature that prevents the metal casing of an appliance from becoming live if a fault occurs. Fuses and circuit breakers protect the circuit from overcurrent.
英国的家庭供电是交流电 (a.c.)，电压约 230 V，频率 50 Hz。家庭布线使用环形干线，火线为棕色，零线为蓝色，地线为绿色/黄色。地线是一项安全措施，当发生故障时可防止电器金属外壳带电。保险丝和断路器可保护电路免受过电流影响。
= V²/R. The kilowatt-hour (kWh) is a unit of energy used for billing: 1 kWh = 3.6 × 10⁶ J.
在直流电路中，元件传递的能量为 E = VIt，功率为 P = VI = I²R = V²/R。千瓦时 (kWh) 是计费使用的能量单位：1 kWh = 3.6 × 10⁶ J。
5. Particle Model of Matter and Density | 物质粒子模型与密度
, and motion of particles. Density ρ is the mass per unit volume: ρ = m/V. Changes of state are physical changes; mass is always conserved during a change of state. The energy needed to change the state of 1 kg of a substance without changing its temperature is called specific latent heat: L = E/m (with units J/kg).
物质由微小粒子组成。粒子模型通过粒子间距、排列和运动方式解释固体、液体和气体之间的差异。密度 ρ 是单位体积的质量：ρ = m/V。状态变化是物理变化；质量在状态变化过程中总是守恒的。使 1 kg 物质发生状态变化而不改变温度所需的能量称为比潜热：L = E/m（单位 J/kg）。
The specific latent heat of fusion (solid–liquid) and vaporisation (liquid–gas) are not the same. During heating, the energy supplied goes into breaking inter-particle bonds, so the temperature stays constant while the state changes.
熔化比潜热（固‑液）和气化比潜热（液‑气）并不相同。加热过程中，提供的能量用于打破粒子间的键合，因此在状态变化时温度保持不变。
6. Atomic Structure and Radioactive Decay | 原子结构与放射性衰变
Atoms consist of a small, dense nucleus containing protons and neutrons, surrounded by electrons in shells. The number of protons determines the element (atomic number Z); the total of protons and neutrons is the mass number A. Isotopes are atoms of the same element with different numbers of neutrons.
原子由包含质子和中子的微小致密原子核及按壳层分布的电子组成。质子数决定元素（原子序数 Z）；质子与中子总数就是质量数 A。同位素是质子数相同但中子数不同的同种元素原子。
Some isotopes are unstable and decay randomly, emitting ionising radiation: alpha particles (helium nuclei, highly ionising, stopped by paper, range a few cm in air), beta particles (fast electrons, moderately ionising, stopped by a few mm of aluminium), and gamma rays (electromagnetic waves, low ionising, reduced by thick lead or several metres of concrete). Nuclear equations must balance mass and charge numbers.
某些同位素不稳定，会发生随机衰变，放出电离辐射：α 粒子（氦核，电离能力很强，一张纸即可阻挡，空气中射程几厘米）、β 粒子（高速电子，中等电离，几毫米铝板可阻挡）和 γ 射线（电磁波，电离能力弱，厚铅板或几米混凝土才能减弱）。核方程必须满足质量数和电荷数守恒。
7. Half-Life and Hazards of Radiation | 半衰期与辐射危害
The half-life of a radioactive isotope is the time taken for the number of unstable nuclei in a sample to halve. It is a constant for a given isotope. Half-life determines how long a radioactive source remains active and influences its safe handling. You must be able to work out half-life from graphs of activity against time, and make predictions about remaining activity or undecayed nuclei.
放射性同位素的半衰期是指样本中不稳定原子核数量减半所需的时间。对于特定同位素，半衰期是一个常数。它决定了放射源保持活性的时长，并影响安全操作方式。你必须能从活度随时间变化的图像中求出半衰期，并对剩余活度或未衰变核的数量做出预测。
Ionising radiation can damage living cells, cause mutations, and lead to cancer. However, it is also used beneficially in medicine (radiotherapy, tracers) and industry (thickness gauges, sterilisation). Contamination is the unwanted presence of radioactive material, whereas irradiation is exposure to radiation without the source being present in the body.
电离辐射会损伤活细胞、导致基因突变并引发癌症。但它也在医学（放射治疗、示踪剂）和工业（测厚仪、灭菌）中有益应用。污染是指不希望出现的放射性物质存在，而辐照则是受到辐射照射但放射源并未进入体内。
8. Forces and Motion | 力与运动
ng both magnitude and direction. A resultant force causes acceleration according to Newton' resultant force, an object either remains stationary or moves with constant velocity (Newton's first law).
力是矢量，有大小和方向。根据牛顿第二定律，合力产生加速度：F = ma。在没有合力的情况下，物体要么保持静止，要么以恒定速度运动（牛顿第一定律）。
y occurs when the drag force equals the weight, resulting in zero resultant force and constant speed. Stopping distance = thinking distance + braking distance. Factors affecting each – speed, reaction time, weather, tyre condition, road surface – must be known.
重力作用下的运动可用 v = u + at, s = {(u+v)/2}t, s = ut + ½at², v² = u² + 2as 来分析（a = ±g，通常取 9.8 m/s²）。当阻力等于重力时，达到终端速度，此时合力为零，速度恒定。制动距离 = 反应距离 + 刹车距离。必须了解影响各段的因素——速度、反应时间、天气、轮胎状况、路面状况。
9. Momentum and Collisions | 动量与碰撞
m is used to analyse collisions and explosions. In a collision, total momentum before equals total momentum after: m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂. Whenever you use this equation, state a positive direction and assign signs to velocities accordingly.
动量 p = mv。动量是矢量，在孤立系统（无外力作用）中守恒。动量守恒定律用于分析碰撞和爆炸。在碰撞中，碰前总动量等于碰后总动量：m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂。使用此公式时，应规定正方向并为速度赋予相应的正负号。
ns how air bags and crumple zones increase collision time, reducing the force experienced.
力等于动量的变化率：F = Δp/Δt。这解释了安全气囊和溃缩区如何延长碰撞时间，从而减小人体受到的力。
10. Waves: Properties and Types | 波：特性与类型
lar to the direction of energy transfer. In longitudinal waves (e.g. sound, seismic P-waves), the oscillations are parallel to the direction of energy transfer. Key wave quantities: amplitude (maximum displacement), wavelength λ, frequency f, period T = 1/f, and wave speed v = fλ.
波传递能量而不传递物质。在横波（如光波、水波、电磁波）中，振动方向与能量传递方向垂直。在纵波（如声波、地震 P 波）中，振动方向与能量传递方向平行。关键波动量：振幅（最大位移）、波长 λ、频率 f、周期 T = 1/f、波速 v = fλ。
tion (except when normally incident). The electromagnetic spectrum ranges from radio waves to gamma rays, all travelling at 3.0 × 10⁸ m/s in a vacuum. Uses and hazards of each region should be known.
所有波都能发生反射、折射和衍射。折射发生在波在边界处速度改变时，引起方向改变（垂直入射时例外）。电磁波谱从无线电波到 γ 射线，在真空中均以 3.0 × 10⁸ m/s 传播。应了解每个波段的应用和危害。
11. Electromagnetism and the Motor Effect | 电磁学与电动机效应
When an electric current flows through a wire, a magnetic field is produced around it. For a long straight wire, the field consists of concentric circles; for a solenoid, the field resembles that of a bar magnet. The strength of an electromagnet can be increased by using a soft iron core, increasing the current, or increasing the number of turns on the coil.
当电流通过导线时，导线周围会产生磁场。对于长直导线，磁场呈同心圆状；对于螺线管，磁场类似于条形磁铁。增强电磁铁强度的方法有：使用软铁芯、增大电流或增加线圈匝数。
d in an external magnetic field experiences a force (the motor effect). The direction of the force is given by Fleming' raight wire perpendicular to a uniform field (B is magnetic flux density, I current, l length of wire in the field). This principle is used in electric motors and loudspeakers.
置于外部磁场中的载流导体会受到一个力（电动机效应）。力的方向由弗莱明左手定则确定。对于与均匀磁场垂直的直导线，力 F = BIl（B 为磁通量密度，I 为电流，l 为导线在磁场中的长度）。这一原理应用于电动机和扬声器。
12. Space Physics and the Universe | 空间物理与宇宙
Our solar system consists of the Sun, eight planets, dwarf planets, moons, asteroids, and comets. Planets orbit the Sun in elliptical orbits, held by gravity. Moons orbit planets. The Earth completes one rotation on its axis in 24 hours (day and night) and one orbit around the Sun in 365¼ days (the year).
太阳系由太阳、八大行星、矮行星、卫星、小行星和彗星组成。行星在引力作用下以椭圆轨道绕太阳运行。卫星绕行星运行。地球自转一周为 24 小时（昼夜交替），绕太阳公转一周为 365¼ 天（一年）。
Stars form from clouds of dust and gas (nebulae) pulled together by gravity. Fusion of hydrogen into helium in the core releases vast amounts of energy, creating a stable main sequence star. Subsequent evolution depends on the star's mass; our Sun will eventually become a red giant and then a white dwarf. The universe began approximately 13.8 billion years ago with the Big Bang. Evidence includes the redshift of light from distant galaxies and the cosmic microwave background radiation. The greater the red shift, the faster a galaxy is moving away from us, supporting the expansion of the universe.
恒星由尘埃和气体云（星云）在引力作用下聚集而成。核心中氢聚变为氦释放巨大能量，形成稳定的主序星。后续演化取决于恒星的质量；太阳最终将变成红巨星，再成为白矮星。宇宙大约 138 亿年前起源于大爆炸。证据包括来自遥远星系光线的红移和宇宙微波背景辐射。红移越大，星系远离我们的速度越快，这支持了宇宙膨胀的理论。
Published by TutorHao | Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图